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http://issues.apache.org/jira/browse/HADOOP-59?page=comments#action_12417960 ]
Owen O'Malley commented on HADOOP-59:
-------------------------------------
I'm sorry that I didn't pay paid attention to this issue earlier.
I think that it is confusing having the cli options segregated. For example, I
have a patch for distcp (aka CopyFiles) that adds a "-i" option to ignore read
errors. With this setup, the user needs to specify the -i *last*. It implies
that the user need to remember what is a generic option versus what is a
command option. (Ok, raise your hand if you can tell me the difference between
"cvs -d foo co bar" and "cvs co -d foo bar". The sad thing is that I do know
and I'm sure a few of you do too. But it certainly does confuse non-experts.)
Furthermore, each application needs to handle --help themselves (and as a side
effect adding a new generic option means updating the usage string in each
application).
I haven't used the commons cli library, but I would have prefered something
less inhertiance-based, more like::
Parser cliParser = new GenericOptionsParser();
cliParser.addOption("i", false, "ignore read errors");
cliParser.parse(args, conf);
boolean ignoreErrors = cliParser.hasOption("i");
> support generic command-line options
> ------------------------------------
>
> Key: HADOOP-59
> URL: http://issues.apache.org/jira/browse/HADOOP-59
> Project: Hadoop
> Type: Improvement
> Components: conf
> Versions: 0.2.0
> Reporter: Doug Cutting
> Assignee: Hairong Kuang
> Priority: Minor
> Fix For: 0.4.0
> Attachments: Tool.java, ToolBase.java, bashfile.patch,
> commons-cli-2.0-SNAPSHOT.jar, genericCommand.patch, toolbase.patch
>
> Hadoop commands should all support some common options. For example, it
> should be possible to specify the namenode, datanode, and, for that matter,
> any config option, in a generic way.
> This could be implemented with code like:
> public interface Tool extends Configurable {
> void run(String[] args) throws Exception;
> }
> public class ToolBase implements Tool extends Configured {
> public final void main(String[] args) throws Exception {
> Configuration conf = new Configuration();
> ... parse config options from args into conf ...
> this.configure(conf);
> this.run();
> }
> }
> public MyTool extends ExcecutableBase {
> public static void main(String[] args) throws Exception {
> new MyTool().main(args);
> }
> }
> The general command line syntax could be:
> bin/hadoop [generalOptions] command [commandOptions]
> Where generalOptions are things that ToolBase handles, and only the
> commandOptions are passed to Tool.run(). The most important generalOption
> would be '-D', which would define name/value pairs that are set in the
> configuration. This alone would permit folks to set the namenode, datanode,
> etc.
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